Back contact photovoltaic module with glass back-sheet

Abstract

An integrated back sheet for a back-contact solar cell module and a back-contact solar cell module made with an integrated glass back-sheet are provided. Processes for making such integrated back-sheets and back-contact solar cell modules are also provided. Elongated electrically conductive wires are mounted on a layer of the integrated back-sheet adhered to the glass back-sheet. The elongated electrically conductive wires of the integrated back-sheet electrically connect to solar cell back contacts when the back-sheet is used in a back-contact photovoltaic module.

What is claimed is: 
     
         1 . A process for making an integrated back-sheet for a back contact solar cell module with a plurality of electrically connected solar cells, comprising:
 providing a polymeric wire mounting layer having opposite first and second sides and having a lengthwise length and direction and a crosswise direction perpendicular to the lengthwise direction;   providing a plurality of elongated electrically conductive wires and adhering said plurality of electrically conductive wires to the first side of said polymeric wire mounting layer in the lengthwise direction of said polymeric wire mounting layer, said electrically conductive wires being substantially aligned with the lengthwise direction of said polymeric wire mounting layer, said plurality of electrically conductive wires each having a cross sectional area of at least 70 square mils along their length, said plurality of electrically conductive wires not touching each other upon being adhered to said polymeric wire mounting layer, and said plurality of electrically conductive wires extending at least two times the length of a solar cell of the back-contact solar cell module;   providing a glass back-sheet, and adhering said second side of said polymeric wire mounting layer to said glass back-sheet;   providing a polymeric interlayer dielectric layer having opposite first and second sides and having a lengthwise length and direction and a crosswise direction perpendicular to the lengthwise direction, and forming openings in said polymeric interlayer dielectric layer, said openings being arranged in a plurality of columns extending in the lengthwise direction of said polymeric interlayer dielectric layer;   arranging the plurality of columns of openings in said interlayer dielectric layer over the electrically conductive wires adhered to the wire mounting layer such that the openings in each column of openings are aligned with and over one of the plurality of electrically conductive wires; and   attaching the polymeric interlayer dielectric layer to polymeric wire mounting layer.   
     
     
         2 . The process for making an integrated back-sheet of  claim 1  wherein said glass back-sheet has a thickness of from 1.5 to 4 mm. 
     
     
         3 . The process for making an integrated back-sheet of  claim 1  wherein the polymeric wire mounting layer is cured before the polymeric interlayer dielectric layer is attached to the wire mounting layer. 
     
     
         4 . The process for making an integrated back-sheet of  claim 3  wherein after the electrically conductive wires are adhered to the polymeric wire mounting layer, the polymeric wire mounting layer is cured by heating the polymeric wire mounting layer to the curing temperature of the polymeric wire mounting layer. 
     
     
         5 . The process for making an integrated back-sheet of  claim 1  wherein said polymeric wire mounting layer is comprised of a polymer selected from poly(vinyl butyral), ionomers, ethylene vinyl acetate, poly(vinyl acetal), polyurethane, poly(vinyl chloride), polyolefins, polyolefin block elastomers, ethylene acrylate ester copolymers, ethylene copolymers, silicone elastomers, polycarbonate resins, epoxy resins, nylon resins and combinations thereof. 
     
     
         6 . The process for making an integrated back-sheet of  claim 5  wherein said polymeric wire mounting layer is an ethylene copolymer comprised of ethylene and one or more monomers selected from the group of consisting of C1-4 alkyl acrylates, C1-4 alkyl methacrylates, methacrylic acid, acrylic acid, glycidyl methacrylate, maleic anhydride and copolymerized units of ethylene and a comonomer selected from the group consisting of C4-C8 unsaturated anhydrides, monoesters of C4-C8 unsaturated acids having at least two carboxylic acid groups, diesters of C4-C8 unsaturated acids having at least two carboxylic acid groups and mixtures of such copolymers, wherein the ethylene content in the ethylene copolymer accounts for 60-90% by weight. 
     
     
         7 . The process for making an integrated back-sheet of  claim 1  wherein said polymeric interlayer dielectric layer is comprised of poly(vinyl butyral), ionomers, ethylene vinyl acetate, poly(vinyl acetal), polyurethane, poly(vinyl chloride), polyolefins, polyolefin block elastomers, ethylene acrylate ester copolymers, ethylene copolymers, silicone elastomers, chlorosulfonated polyethylene, epoxy and combinations thereof. 
     
     
         8 . The process for making an integrated back-sheet of  claim 1  further comprising the step of selectively cutting one or more of said electrically conductive wires at one or more selected points along the length of said electrically conductive wires. 
     
     
         9 . A process for making a back-contact solar cell module, comprising:
 providing a solar cell array of at least four solar cells each having a front light receiving surface, an active layer that generates an electric current when said front light receiving surface is exposed to light, and a rear surface opposite said front surface, said rear surface having positive and negative polarity electrical contacts thereon, at least two of the solar cells of the solar cell array arranged in a column;   providing a polymeric wire mounting layer having opposite first and second sides and having a lengthwise direction and a crosswise direction perpendicular to the lengthwise direction;   providing a plurality of elongated electrically conductive wires and adhering said plurality of electrically conductive wires to the first side of said polymeric wire mounting layer in the lengthwise direction of said polymeric wire mounting layer, said electrically conductive wires being substantially aligned with the lengthwise direction of said polymeric wire mounting layer, said plurality of electrically conductive wires each having a cross sectional area of at least 70 square mils along their length, said plurality of electrically conductive wires not touching each other upon being adhered to said polymeric wire mounting layer, and said plurality of electrically conductive wires extending at least the length of a column of the solar cells in the solar cell array;   providing a polymeric interlayer dielectric layer having opposite first and second sides and having a lengthwise length and direction and a crosswise direction perpendicular to the lengthwise direction, and forming openings in said polymeric interlayer dielectric, said openings being arranged in a plurality of columns extending in the lengthwise direction of said polymeric interlayer dielectric layer;   placing the interlayer dielectric layer between the rear surface of the solar cells of the solar cell array and the first side of the wire mounting layer, and arranging the plurality of columns of openings in said interlayer dielectric layer over the electrically conductive wires adhered to the wire mounting layer such that the openings in each column of openings are aligned with and over one of the plurality of electrically conductive wires, and aligning the openings in said interlayer dielectric layer with the positive and negative polarity contacts on the rear surfaces solar cells of the solar cell array, wherein said positive and negative polarity electrical contacts on said solar cells are electrically connected to said electrically conductive wires through the openings in said polymeric interlayer dielectric layer;   adhering said polymeric interlayer dielectric layer to said first surface of the polymeric wire mounting layer and to said rear surface of the solar cells of the solar cell array;   providing a glass back-sheet, and attaching said second side of said polymeric wire mounting layer to said glass back-sheet.   
     
     
         10 . The process for making a back-contact solar cell module of  claim 9  wherein the polymeric wire mounting layer is cured before the polymeric interlayer dielectric layer is attached to the wire mounting layer. 
     
     
         11 . The process for making a back-contact solar cell module of  claim 10  wherein after the electrically conductive wires are adhered to the polymeric wire mounting layer, and the polymeric wire mounting layer is cured by heating the polymeric wire mounting layer to the curing temperature of the polymeric wire mounting layer. 
     
     
         12 . The process for making a back-contact solar cell module of  claim 9  wherein said polymeric wire mounting layer and said interlayer dielectric layer are comprised of a polymer selected from poly(vinyl butyral), ionomers, ethylene vinyl acetate, poly(vinyl acetal), polyurethane, poly(vinyl chloride), polyolefins, polyolefin block elastomers, ethylene acrylate ester copolymers, ethylene copolymers, silicone elastomers, polycarbonate resins, epoxy resins, nylon resins and combinations thereof. 
     
     
         13 . An integrated back sheet for a solar cell module with a plurality of electrically connected solar cells, comprising:
 a polymeric wire mounting layer having opposite first and second sides and having a lengthwise length and direction and a crosswise direction perpendicular to the lengthwise direction, said polymeric wire mounting layer having a length of at least two times the length of a solar cell in the solar cell module;   a plurality of elongated electrically conductive wires adhered to the first side of said polymeric wire mounting layer in the lengthwise direction of said polymeric wire mounting layer, said electrically conductive wires being substantially aligned with the lengthwise direction of said polymeric wire mounting layer, said plurality of electrically conductive wires each having a cross sectional area of at least 70 square mils along their length, said plurality of electrically conductive wires not touching each other upon being adhered to said polymeric wire mounting layer, and said plurality of electrically conductive wires extending at least two times the length of a solar cell in the solar cell module, at least one of said electrically conductive wires being cut at at least one selected point along the length of said electrically conductive wires; and   a glass back-sheet attached to the second side of said polymeric wire mounting layer.   
     
     
         14 . A solar cell module, comprising:
 a solar cell array of at least four solar cells arranged in at least one column having a length, each of said solar cells having a front light receiving surface, an active layer that generates an electric current when said front light receiving surface is exposed to light, and a rear surface opposite said front light receiving surface, said rear surfaces having positive and negative polarity electrical contacts thereon;   a polymeric wire mounting layer having opposite first and second sides and having a lengthwise direction and a crosswise direction perpendicular to the lengthwise direction;   a plurality of elongated electrically conductive wires adhered to the first side of said polymeric wire mounting layer in the lengthwise direction of said polymeric wire mounting layer, said electrically conductive wires being substantially aligned with the lengthwise direction of said polymeric wire mounting layer, said plurality of electrically conductive wires each having a cross sectional area of at least  70  square mils along their length, said plurality of electrically conductive wires not touching each other, and said plurality of electrically conductive wires extending at least the length of a column of the solar cells in the solar cell array;   a polymeric interlayer dielectric layer having opposite first and second sides and having a lengthwise length and direction and a crosswise direction perpendicular to the lengthwise direction, said polymeric interlayer dielectric layer having openings arranged in a plurality of columns extending in the lengthwise direction of said polymeric interlayer dielectric layer;   said interlayer dielectric layer adhered to the rear surface of the solar cells of the solar cell array and to the first side of the wire mounting layer, wherein the plurality of columns of openings in said interlayer dielectric layer are arranged over the electrically conductive wires adhered to the wire mounting layer such that the openings in each column of openings are aligned with and over one of the plurality of electrically conductive wires, and wherein the openings in said interlayer dielectric layer are aligned with the positive and negative polarity contacts on the rear surfaces solar cells of the solar cell array, wherein said positive and negative polarity electrical contacts on the rear surface of said solar cells are electrically connected to said electrically conductive wires through the openings in said polymeric interlayer dielectric layer; and   a glass back-sheet attached to said second side of said polymeric wire mounting layer.   
     
     
         15 . The solar cell module of  claim 14  wherein said polymeric wire mounting layer and said interlayer dielectric layer are comprised of a polymer selected from poly(vinyl butyral), ionomers, ethylene vinyl acetate, poly(vinyl acetal), polyurethane, poly(vinyl chloride), polyolefins, polyolefin block elastomers, ethylene acrylate ester copolymers, silicone elastomers, polycarbonate resins, epoxy resins, nylon resins and combinations thereof. 
     
     
         16 . The solar cell module of  claim 14  wherein said glass back-sheet has a thickness of from 1.5 to 4 mm. 
     
     
         17 . The solar cell module of  claim 14  wherein the electrically conductive wires are comprised of metal selected from copper, nickel, tin, silver, aluminum, and combination thereof, and wherein the electrically conductive wires are ribbon-shaped metal wires having a width and thickness wherein the wire width is at least three times greater than the wire thickness. 
     
     
         18 . A solar cell module, comprising:
 a solar cell array of at least four solar cells each having a front light receiving surface, an active layer that generates an electric current when said front light receiving surface is exposed to light, and a rear surface opposite said front light receiving surface, said rear surface having positive and negative polarity electrical contacts thereon, said solar cell array having a length and width;   a glass back-sheet, having first and second opposite sides, said glass back sheet having a length greater than or equal to the length of said solar cell array and a width greater than or equal to the width of said solar cell array;   a plurality of electrically conductive wires disposed between said glass back-sheet and said solar cell array and supported by said first side of said glass back-sheet, said electrically conductive wires being substantially aligned with the length of the glass back-sheet, said electrically conductive wires having a length of at least two times the length of a solar cell of the solar cell array, and said electrically conductive wires having a cross sectional area of at least  70  square mils along their length, said plurality of electrically conductive wires not touching each other;   a polymeric insulating layer having opposite first and second sides disposed between said plurality of electrically conductive wires and said solar cell array, said first side of said polymeric insulating layer being adhered to the rear surface of the solar cells of the solar cell array and said second side of said polymeric insulating layer being adhered to said plurality of electrically conductive wires, said polymeric insulating layer having openings over the positive and negative contacts on the rear surface of the solar cells of the solar cell array, wherein said positive and negative contacts on said solar cells are electrically connected to one of said electrically conductive wires through the opening in said polymeric insulating layer over the electrical contacts.   
     
     
         19 . The solar cell module of  claim 18  wherein said second side of said polymeric insulating layer is adhered to said first side of said glass back-sheet. 
     
     
         20 . The solar cell module of  claim 18 , further comprising a polymeric encapsulant layer, said polymeric encapsulant layer disposed between said plurality of electrically conductive wires and said first side of said glass back-sheet, said polymeric encapsulant layer having opposite first and second sides, the first side of said polymeric encapsulant layer being adhered to the second side of the polymeric insulating layer such that the plurality of electrically conductive wires are sandwiched between said polymeric encapsulant layer and said polymeric insulating layer, and the second side of said polymeric encapsulant layer being adhered to said first side of said glass back-sheet.